Image forming apparatus and control method for same

A control method for an image forming apparatus,

• the image forming apparatus comprising:
• a first belt member rotatably extended around multiple roller members;
• a first image forming unit including at least one first color image carrier disposed facing an outer surface of the first belt member, the first image forming unit to form a first image on the at least one first color image carrier;
• a primary transfer member to transfer the first image formed on the at least one first color image carrier onto the first belt member;
• a secondary transfer mechanism to transfer the first image formed on the first belt member onto a recording medium at a secondary transfer position;
• a second image forming unit to form a second image on a separate second image carrier separate from the at least one first color image carrier, the separate second image carrier disposed either upstream or downstream from the secondary transfer position in a direction of conveyance of the recording medium;
• a direct transfer member to transfer the second image formed on the separate second image carrier directly onto the recording medium at a direct transfer position;
• a second belt member rotatably extended around multiple roller members to carry the recording medium to the direct transfer position and then to the secondary transfer position;
• a controller to transfer reference pattern images formed on the at least one first color image carrier and the separate second image carrier onto one of the first belt member and the second belt member;
• and
• an image detector disposed facing one of the first belt member and the second belt member to detect positional deviation of transferred images from the reference pattern images;
• and
• the control method comprising:
• conveying the reference pattern images to the image detector;
• causing the mage detector to detect the reference pattern images;
• and
• adjusting one or more image forming conditions of the image forming apparatus to prevent positional deviation of the transferred images from the reference pattern images based on detection results obtained by the image detector.